Pattern controlled feed mechanism

ABSTRACT

For stitching along a curve and/or rectilinearly a sewing machine (or the like) includes in its bed, in lieu of conventional feed dog mechanism or the like, a cam of desired interchangeable pattern serving also as a work hold-down, and feed mechanism for progressing the work and cam relative to the operating zone of a conventionally reciprocable needle. The feed mechanism desirably comprises a pair of idler rolls engageable with one side, for example the exterior of the cam, and a drive roll engageable with the opposite or interior side of the cam and biased toward the idler rolls substantially between them.

United States Patent 1 Mercaldi PATTERN CONTROLLED FEED MECHANISM [75] Inventor: William B. Mercaldi, Beverly, Mass. [73] Assignee: USM Corporation, Boston, Mass.

[22] Filed: Mar. 27, 1972 [21] Appl. No.: 238,034

[52] U.S. Cl. 112/102 [51] Int. Cl. D05c 3/02 [58] Field of Search 112/102, 103, 98

[56] References Cited UNITED STATES PATENTS 797,308 8/1905 Nassberg 112/98 X 1,431,591 10/1922 Lucy 1,575,285 3/1926 Sibbald et a1. 3,018,743 l/l962 Johnson 112/102 FOREIGN PATENTS OR APPLICATIONS 402,583 5/1966 Switzerland 112/102 June 26, 1973 Primary Examiner-Alfred R. Guest Attorney-Carl E. Johnson et a1.

[57] ABSTRACT For stitching along a curve and/or rectilinearly a sewing machine (or the like) includes in its bed, in lieu of conventional feed dog mechanism or the like, a cam of desired interchangeable pattern serving also as a work hold-down, and feed mechanism for progressing the work and cam relative to the operating zone of a conventionally reciprocable needle. The feed mechanism desirably comprises a pair of idler rolls engageable with one side, for example the exterior of the cam, and a drive roll engageable with the opposite or interior side of the cam and biased toward the idler rolls substantially between them.

PATTERN CONTROLLED FEED MECHANISM BACKGROUND OF THE INVENTION In the production of many industrial items as well as in the garment trades securement as by sewing operations is often performed in repetitive pattern. This is to say that the seams follow identical or similar configuration, usually in a plane and along a margin and often include convex curvature, concave-convex shapes, or such shapes intersperced with rectilinear portions.

Different mechanisms, usually complex in nature, have hitherto been provided for guidance of sewing in these regular and or irregular patterns. Edge guidance and numerical control are examples, the latter being relatively costly and the former not always being dependable in view of the yieldable contour or profile of many limp materials when edge gaged.

Since a large portion of the stitching paths to be produced do not involve sharp vertices and irregularities, but are comprised mainly of straight and/or arcuate portions wherein the radius of curvature is not smaller than, say, one-half inch, there exists considerable need for uncomplicated automatic guidance mechanism applicable to conventional stitchers for handling such work. An operator can then concentrate largely on introducing and removing the individual work pieces.

SUMMARY OF THE INVENTION In view of the foregoing it is an object of this invention to provide, for use with a sewing or other work securing machine, a simple pattern controlled work feeding mechanism by means of which a predetermined shape of seam may be reproduced with only loading and unloading attention required of an operator.

For the purpose above stated a feature of the invention resides in the provision of an open or preferably hollow pattern cam of selected contour, the cam to serve as a work hold-down as the work is guided on a work supporting bed relative to a reciprocable tool such as a needle, and cam feeding mechanism for progressing the work relative to the operating zone of the needle. As shown herein the cam feeding mechanism preferably has frictional engagement with opposite upstanding wall portions of the cam at a locality adjacent to the needle.

A further feature of the invention relates to the provision, in a pattern controlled sewing machine, of mecha-. nism for separating a guide cam from its feed mechanism whereby at termination of a seam the work may be removed and a new work piece conveniently introduced.

BRIEF DESCRIPTION OF THE DRAWINGS The foregoing and other features of the invention will now be more particularly described in connection with an illustrative embodiment and with reference to the accompanying drawings thereof, in which:

FIG. 1 is a view in front elevation with portions broken away of a pattern following mechanism operable in conjunction with the head of a double needle sewing machine.

FIG. 2 is a section taken on the line II-II of FIG. 1.

FIG. 3 is a detail view in side elevation indicating work and cam guide mechanism shown in FIGS. 1 and 2, and

FIG. 4 is a plan view of mechanism for moving the cam guide mechanism heightwise.

DESCRIPTION OF PREFERRED EMBODIMENT In FIG. 1 a stationary sewing machine head generally designated 10 includes a vertically reciprocable needle bar 12 carrying, in this instance, a pair of needles 14,14. The machine 10 may be devoid of conventional work feed dog mechanism, but includes a horizontal bed 16 for slidably supporting a pair of superimposed work pieces W,W (FIGS. 1,2) which, in this case are shown circular and are to be marginally sewed as by a concave convex double seam S (FIG. 2). Clearly the work pieces may be of any desired shape and underlie, at least in part, a pattern or cam shaped guide rail 18 (FIGS. 1-3) which is of selected contour and preferably is hollow and rigid.

As shown in FIG. 2 for purposes of illustration only the selected pattern cam 18 has portions which are convex, concave and rectilinear. The latter, in this example, extend outside the edges of the work pieces thereby defining, in the exemplary product to be stitched, an inlet or neck area 20 into which filler material may be introduced to fill a pouch-like space between the plies afforded by the circular portion of the pattern. It will be understood that application of the invention is not limited to any particular work piece material, nor is it necessarily restricted to use with a sewing machine since other mechanized forms of securement such as cementing, stapling, etc. may likewise be employed with the invention.

In disposing the pattern cam 18 on the work pieces W,W its exterior contour determines where a correspondingly shaped seam is to be sewed. Accordingly a seam receiving (or other securing) margin of the work will extend on the bed 16 between the pattern cam 18 and an external edge of the work pieces W, the cam holding the work outspread during machine operation.

Mechanism for jointly feeding the pattern cam 18 and work pieces W progressively past the operating zone of the needles 14 will next be described. Vertical ways or guide slots 22,22 (FIGS.1,4) affixed to the machine head 10 slidably receive a bracket 24 and a drive motor-reducer 26 mounted thereon. A depending rotary output shaft 28 of the motor is operatively connected by a pair of swivel joints 30,32 and a link 34 to a drive roll 36 progressively engageable with the inside wall 38 of the pattern cam 18. For yieldably urging the drive roll 36 into frictional driving engagement the roll is carried by a rotatable pin 40 in a baring block 42, and the latter is 'acted on by a compression spring 44 nested in the base of the bracket 24.

The drive roll 36 is disposed midway between a pair of cooperative idler rolls 46,46 engageable with the exterior of the pattern cam 18 and straddling the operating zone of the needles 14. The idler rolls 46 are respectively mounted in blocks 48 (FIG. 3) having adjustable tongue and groove connection with the bracket 24, whereby a range of thickness in the rails of pattern earns 18 can be accommodated by means of adjusting set screws 50,50 respectively securing the blocks 48 to the bracket 24.

For raising a pattern cam 18 from its operative position at the end of an operating cycle in order to remove a completed work piece assembly and enable insertion of new work pieces to be stitched or the like, a fluidpressure device in the form of a dual acting piston rod 52 (FIG. 1) and a cylinder 54 is secured to the top of the head 10. Upon actuation of the device, as by a switch not shown, a lever 56 (FIGS. 1 and 4) pivoted at 58 and connected to the rod 52 and to a link 60 coupled to the bracket 24 is enabled to elevate the drive mechanism with the pattern cam, the latter being shifted from the bed to its dash line position to facilitate reloading of next work pieces.

It will be appreciated that if it is desired to change the pattern of a seam, manual retraction of the drive roll 36 by compressing the spring 44 will release the cam 18 and allow substitution of an alternate pattern as desired. It will also be understood that a suitable automatic needle-up positioning mechanism is desirable to insure that the needles 14 at the end of a seam are raised to positions as shown in FIG. 1 to avoid interfering with work removal.

The machine operation will now be briefly reviewed assuming a selected pattern cam 18 rests upon work pieces W to be assembled. The drive roll 36 is rotated about its vertical axis at a fixed speed determined by the ratio of the reducer accompanying the drive motor 26 and appropriate to the number of stitches per inch desired. Operation of the motor-reducer may be operator-controlled or automatically started in response to lowering of the drive roll 36 to a level wherein the pattern cam is engaged thereby. Progressive portions of the cam will be frictionally fed past the needles 14 by the coaction of the roll 36 and the idlers 46 and simultaneously slide the work piece margins through their operating zone. As a convex operating path shifts to rectilinear or to concave curvature as dictated by corresponding portions of the cam 18, the drive roll 36 is displaced and yields radially relative to the idlers as necessary while maintaining substantially uniform fric tional feeding force and hence constant linear speed of the work. The rolls 36 and 46,46 at all times maintain the fabric feeding direction in the locality of the tool or needle 14 tangential-to the contour of the pattern cam 18.

It is to be noted that work pieces W which afford no stretch or give may prove difficult to guide if a rapid feed rate is required since the machine, in-its simplest embodiment, contemplates no mechanism for insuring that work advance occurs only when the needle is disengaged. In general the work is slidingly moved by the cam 18 to present successive portions to the needles 14 in a pattern paralleling the exterior contour of the cam. On guiding the work pieces W out from under the needles and then back under them as done by the closed illustrative cam 18, a gap in the otherwise continuous seam is created. Substitution of cams is easily made when necessary to produce any of a great variety of securement patterns. While the described arrangement is preferred, it is recognized as within the scope of this invention, if need be, to have the powered roll externally engage the guide cam 18, and/or to dispose the needle 14 within and adjacent to the inner wall of the cam 18.

As above indicated a closed pattern cam 18 is often preferred. This enables automatic re-set of the cam to the same initial starting point even though stitching (or other processing) may not have extended over an entirely closed path. While the cam 18 is raised from the work and bed, the rolls may progress the perimeter of the cam idly to a suitably marked starting point.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent of the United States is:

1. For use on the bed of a machine having a tool for securing superimposedv work pieces together, a guide cam slidable in hold-down relation on the bed and of selected contour for frictionally sliding the work pieces on the bed, and feed mechanism for progressively advancing the guide cam jointly with the work relative to the operating zone of the tool.

2. A machine as in claim 1 wherein the cam is hollow, and the feed mechanism comprises rotatable means frictionally engageable with upstanding opposite surfacesof the guide cam in the operative zone of the tool.

3. A machine as in claim 2 wherein the rotatable means includes a drive roll in yieldable engagement with one vertical side wall of the guide cam, and at least one idler roll in cooperative engagement with an opposed vertical side wall of the cam.

4. A machine as in claim 3 wherein the drive roll engages an interior wall of the cam, and a pair of idler rolls engage an exterior wall of the cam, the idler rolls being disposed to straddle the operating zone of the tool.

5. A machine as in claim 4 wherein spring means is arranged to urge the drive roll and idler rolls into wall clamping relation to the guide cam, and mechanism is operable to move the cam heightwise into and out of hold-down relation to facilitate removal and reloading of work pieces.

6. In a sewing machine, a head having stitch forming means including a reciprocable needle, 21 bed for slidably supporting work pieces engageable by the needle, a pattern cam disposable on the work pieces and having an upstanding rail portion extending in a contour corre sponding to the seam to be sewn, and power feed mechanism operable progressively on the rail portion adjacent to the operating zone of the needle, said mechanism including friction means rotatable about a vertical axis.

7. A machine as set forth in claim 6 wherein the feed mechanism is driven by a motor reducer unit, and power means operable to shift the feed mechanism and the pattern cam jointly heightwise toward and from operative relation with the bed.

8. A machine as set forth in claim 6 wherein the friction means is a cylindrical roll carried by a bearing block and engageable with the interior of the cam opposite to the locality of the needle, and a pair of smaller diameter rolls one at either side of said locality clampingly engage the exterior of the cam.

9. A machine as set forth in claim 7 wherein the motor reducer unit rotatably drives a roll engaging the rail portion, and an output shaft of the unit is operatively coupled to the roll by means of universal joints. I! t i 

1. For use on the bed of a machine having a tool for securing superimposed work pieces together, a guide cam slidable in holddown relation on the bed and of selected contour for frictionally sliding the work pieces on the bed, and feed mechanism for progressively advancing the guide cam jointly with the work relative to the operating zone of the tool.
 2. A machine as in claim 1 wherein the cam is hollow, and the feed mechanism comprises rotatable means frictionally engageable with upstanding opposite surfaces of the guide cam in the operative zone of the tool.
 3. A machine as in claim 2 wherein the rotatable means includes a drive roll in yieldable engagement with one vertical side wall of the guide cam, and at least one idler roll in cooperative engagement with an opposed vertical side wall of the cam.
 4. A machine as in claim 3 wherein the drive roll eNgages an interior wall of the cam, and a pair of idler rolls engage an exterior wall of the cam, the idler rolls being disposed to straddle the operating zone of the tool.
 5. A machine as in claim 4 wherein spring means is arranged to urge the drive roll and idler rolls into wall clamping relation to the guide cam, and mechanism is operable to move the cam heightwise into and out of hold-down relation to facilitate removal and reloading of work pieces.
 6. In a sewing machine, a head having stitch forming means including a reciprocable needle, a bed for slidably supporting work pieces engageable by the needle, a pattern cam disposable on the work pieces and having an upstanding rail portion extending in a contour corresponding to the seam to be sewn, and power feed mechanism operable progressively on the rail portion adjacent to the operating zone of the needle, said mechanism including friction means rotatable about a vertical axis.
 7. A machine as set forth in claim 6 wherein the feed mechanism is driven by a motor reducer unit, and power means operable to shift the feed mechanism and the pattern cam jointly heightwise toward and from operative relation with the bed.
 8. A machine as set forth in claim 6 wherein the friction means is a cylindrical roll carried by a bearing block and engageable with the interior of the cam opposite to the locality of the needle, and a pair of smaller diameter rolls one at either side of said locality clampingly engage the exterior of the cam.
 9. A machine as set forth in claim 7 wherein the motor reducer unit rotatably drives a roll engaging the rail portion, and an output shaft of the unit is operatively coupled to the roll by means of universal joints. 